Prof. J.P.N. Mishra
Metabolism, the characteristics of life, refers to several chemical reactions of the body. Because chemical reactions either require or release energy, the body's metabolism may be thought of as an energy-balancing act between anabolic and catabolic reactions. For any chemicals reaction oxygen is must which we get oxygen from the process of respiration only The organs involved in respiration transport oxygen. In transportation of oxygen, oxygen is bound to carry substances in the blood. Oxygen carrier respiratory pigment is Hb (Haemoglobin). In the cells and tissues of body the oxygen tension is considerably low. The oxygen is accordingly liberated from oxy-haemoglobin and diffuses from the blood through thin capillary walls into the cells. The reduced Hb is further transported via blood to the lungs and the cycle is repeated, while the oxygen that has diffused into the cells is utilized in the oxidation of carbohydrates and other food materials, resulting in the release of carbon dioxide and energy. Within each cell glucose is first metabolized to pyruvic acid and then, if there is supply of oxygen, into carbon dioxide and water. It is when hydrogen atoms are combined with oxygen that most of the energy is released in the cell. By storing energy as ATP (Adenosine Tri Phosphate) molecules, the cell can utilize this energy for its other activities as needed. Overall, the energy, which is utilized for the breakdown of food materials, involves anabolic processes (form new chemical bonds) and the process, which provides that energy through catabolic reactions, is catabolism (release the available chemical energy in organic molecules).
Anabolic reactions are mostly energy requiring reactions and catabolic reactions provide the energy needed to drive anabolic reactions. This coupling of energy requiring and energy releasing reactions is achieved through ATP. ATP stores energy derived from catabolic reactions and releases it later to derive anabolic reactions. These reactions occur in every cell in the body and provide the cell's chief source of energy. And without oxygen it is not possible. So we can say that oxygen is the basic need of every human being and it is the process of respiration only, through which we get oxygen (Tortora at. el., 2006).
Fig 1-13 Structure of respiratory system
